Energetic Characterization of Faujasite Zeolites Using a Sensor Gas Calorimeter
Energetic Characterization of Faujasite Zeolites Using a Sensor Gas Calorimeter
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DOI：
10.3390/catal11010098
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发表时间：
2021-01-01
期刊：
影响因子：
3.9
通讯作者：
Bathen, Dieter
中科院分区：
文献类型：
--
作者：
Mauer, Volker;Blaeker, Christian;Bathen, Dieter
除了吸附机理之外，在放热吸附期间释放的热量影响在多相催化期间随后的化学反应。这两个步骤都取决于催化剂的结构和表面化学。典型催化剂的实例是八面沸石。因此，对于八面沸石，在系统的研究中，Si/Al比和Na+和Ca ~（2+）阳离子的数目对吸附热的影响进行了研究。NaX（钠型X八面沸石）和NaY（钠型Y八面沸石）沸石之间的比较表明，八面沸石中较高的Si/Al比和因此较少数量的阳离子导致较低的负载量和热。Na+阳离子与Ca 2+阳离子的交换对吸附过程也有影响。负荷和热量首先在低交换度下略有下降，并随着钙含量的增加而显着增加。如果多相催化需要更强的相互作用，那么CaNaX沸石必须具有高于53%的交换度。能量贡献表明，最高质量的吸附位III和III'对负载依赖的吸附热作出贡献，其比吸附位II大约1.4倍（位III）和约1.8倍（位III'）。
In addition to the adsorption mechanism, the heat released during exothermic adsorption influences the chemical reactions that follow during heterogeneous catalysis. Both steps depend on the structure and surface chemistry of the catalyst. An example of a typical catalyst is the faujasite zeolite. For faujasite zeolites, the influence of the Si/Al ratio and the number of Na+ and Ca2+ cations on the heat of adsorption was therefore investigated in a systematic study. A comparison between a NaX (Sodium type X faujasite) and a NaY (Sodium type Y faujasite) zeolite reveals that a higher Si/Al ratio and therefore a smaller number of the cations in faujasite zeolites leads to lower loadings and heats. The exchange of Na+ cations for Ca2+ cations also has an influence on the adsorption process. Loadings and heats first decrease slightly at a low degree of exchange and increase significantly with higher calcium contents. If stronger interactions are required for heterogeneous catalysis, then the CaNaX zeolites must have a degree of exchange above 53%. The energetic contributions show that the highest-quality adsorption sites III and III' make a contribution to the load-dependent heat of adsorption, which is about 1.4 times (site III) and about 1.8 times (site III') larger than that of adsorption site II.